Major+Material-Glass

media type="youtube" key="2xzf3Cgz99I?fs=1" height="268" width="336" align="right"Glass Glass is one of the major materials used in making a thermometer. The main materials in glass are limestone and quartz sand, or silica. Limestone is extracted from underground mines. Limestone is formed of calcium carbonate and magnesium. Miners usually blow the ground up so they can start drilling. Silica is made when lightning strikes sand. Silica is usually extracted from the earth's crust. This sand is extracted and mixed in with the limestone. Glass makers melt these two substances together and wait until it cools. After it cools, glass is the outcome. This is when glass-blowers blow the glass into different forms and shapes. Once it is blown and solid, it can be stained. Glass blowing started around 50 BC. Glass was first made by the Sumerian Civilization. The people of this civilization mixed sand and silica is very hot forms and when it cooled, it formed glass. Stained glass windows are used in churches, mostly. The Egyptians and Romans colored glass to make beads for jewelry and vases. Glass is one of the most important things in making a thermometer. 